Geology and Nonrenewable Minerals Chapter 9

Key Concepts Major geologic processes Rocks and the rock cycle Finding and extracting mineral resources Environmental effects of mining Enough nonrenewable resources for the future?

General Mining Law of 1872 Original purpose of the law Impact on US public lands Benefits to mining companies Costs to the public Environmental issues Laws in other countries How Would You Vote exercise Fig. 12-1, p. 269

General Mining Law of 1872 Fig. 12-1, p. 269

Internal Geologic Processes What is geology? Earth’s internal structure Core Mantle Crusts (continental and oceanic) Plate tectonics

General Structure of the Earth Oceanic crust Continental crust Atmosphere Vegetation and animals Biosphere Lithosphere Soil Upper mantle Crust Asthenosphere Rock Lower mantle Core Mantle Crust (soil and rock) Biosphere (living and dead organisms) Hydrosphere (water) Lithosphere (crust, top of upper mantle) Atmosphere (air) Fig. 3-5, p. 38

Earth’s Crust and Upper Mantle Abyssal hills Folded mountain belt Abyssal floor Oceanic ridge Abyssal floor Trench Craton Volcanoes Continental rise Oceanic crust (lithosphere) Continental slope Abyssal plain Continental shelf Abyssal plain Continental crust (lithosphere) Mantle (lithosphere) Mantle (lithosphere) Mantle (asthenosphere) Fig. 12-2, p. 271

Plate Tectonics Tectonic plates Lithosphere Plate tectonics and biological evolution

Plate Tectonics Fig. 12-3, p. 272 Spreading center Oceanic tectonic Ocean trench Collision between two continents Plate movement Plate movement Tectonic plate Oceanic crust Oceanic crust Subduction zone Continental crust Continental crust Material cools as it reaches the outer mantle Cold dense material falls back through mantle Mantle convection cell Hot material rising through the mantle Two plates move towards each other. One is subducted back into the mantle on falling convection current. Mantle Hot outer core Inner core Inner core Fig. 12-3, p. 272

Earth’s Major Tectonic Plates EURASIAN PLATE ANATOLIAN PLATE NORTH AMERICAN PLATE JUAN DE FUCA PLATE CHINA SUBPLATE CARIBBEAN PLATE PHILIPPINE PLATE ARABIAN PLATE AFRICAN PLATE PACIFIC PLATE SOUTH AMERICAN PLATE NAZCA PLATE INDIAN-AUSTRLIAN PLATE SOMALIAN SUBPLATE ANTARCTIC PLATE Convergent plate boundaries Divergent boundaries Transform faults Fig. 12-4, p. 273

Types of Plate Boundaries Divergent Convergent Transform Fig. 12-5, p. 274

Types of Plate Boundaries Lithosphere Asthenosphere Oceanic ridge at a divergent plate boundary Fig. 12-5a, p. 274

Types of Plate Boundaries Volcanic island arc Trench Lithosphere Rising magma Asthenosphere Subduction zone Trench and volcanic island arc at a convergent plate boundary Fig. 12-5b, p. 274

Types of Plate Boundaries Fracture zone Transform fault Lithosphere Asthenosphere Transform fault connecting two divergent plate boundaries Fig. 12-5c, p. 274

External Earth Processes Erosion Physical (mechanical) weathering: frost wedging Chemical weathering Biological weathering

Minerals and Rocks Minerals (as examples: quartz and diamonds) Rocks Rock types Igneous (granite and basalt) Sedimentary (sandstone and limestone) Metamorphic (marble and slate) Rock cycle

The Rock Cycle Fig. 12-6, p. 275 Erosion Transportation Weathering Deposition Igneous Rock Granite, pumice, basalt Sedimentary Rock sandstone, limestone Heat, pressure Cooling Magma (molten rock) Heat, pressure, stress Melting Metamorphic Rock Slate, marble, gneiss quartzite Fig. 12-6, p. 275

Mineral Resources Generally nonrenewable Metallic, nonmetallic, and energy resources Ores

Categories of Mineral Resources Identified Undiscovered Reserves Other Fig. 12-7, p. 276

Categories of Mineral Resources Undiscovered Identified Reserves Economical Other resources Decreasing cost of extraction Not economical Decreasing certainty Known Existence Fig. 12-7, p. 276

Finding Mineral Resources Aerial and satellite images Radiation detectors Magnetometers Gravimeters Seismic surveys Chemical analyses

Extracting Mineral Deposits Surface mining Subsurface mining Overburden Spoils

Mining Methods Open-pit (surface mining) Area strip mining (surface) Contour strip mining (surface) Mountaintop removal (surface) Subsurface mining Hazards and environmental tradeoffs of subsurface mining

Open-pit Mine Fig. 12-8, p. 277

Spoil from an Unrestored Area Strip Mine Fig. 12-9, p. 277

Contour Strip Mining Undisturbed Land Overburden Highwall Coal seam Pit Bench Coal seam Spoil Banks Fig. 12-10, p. 277

Mountaintop Mining Fig. 12-11, p. 278

Environmental Effects of Using Mineral Resources Disrupting the land surface Subsidence Toxic mining waste Acid mine drainage Air pollution Toxic holding ponds

Environmental Effects of Mineral Use Natural Capital Degredation Extracting, Processing, and Using Nonrenewable Mineral and Energy Resources Steps Environmental Effects Disturbed land; mining accidents; health hazards; mine waste dumping;oil spills and blowouts; noise; ugliness; heat Mining Exploration, extraction Processing Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat Transportation, purifi- cation, manufacturing Use Noise; ugliness; thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat transportation or trans- mission to individual user, eventual use, and discarding Fig. 12-12, p. 279

Processing of Mineral Resources Ore mineral Gangue Tailings Smelting Products Disposal or recycling

Typical Life Cycle of a Metal Resource Surface mining Metal ore Separation of ore from gangue Smelting Melting metal Conversion to product Discarding of product (Scattered in environ-ment) Reuse Recycling Fig. 12-13, p. 279

Environmental Limits to Resource Extraction Environmental damage: a major mining problem Ore grade Including environmental costs in products How Would You Vote exercise

Supplies of Mineral Resources Available supply and use Economic depletion Five choices after depletion Recycle or reuse Waste less Use less Find a substitute Do without Depletion time Economics Finding alternatives

Depletion Curves for a Nonrenewable Resource Mine, use, throw away; no new discoveries; rising prices Recycle; increase reserves by improved mining technology, higher prices, and new discoveries B Production Recycle, reuse, reduce consumption; increase reserves by improved mining technology, higher prices, and new discoveries C Present Depletion time A Depletion time B Depletion time C Fig. 12-14, p. 280 Time

Economics and Supplies of Nonrenewable Resources Roll of economics in mining Standard economic theory Limited free market in developed countries Government subsidies of mining 1872 US General Mining Law Economic problems of developing new mines

Mining Lower-grade Ores New extraction technologies are needed Factors that limit mining lower-grade ores Costs Supplies of freshwater Environmental impacts Biomining: microorganisms and in-situ mining

Nanotechnology Revolution Buckyballs Molecular economy Possible achievements of nanotechnology Possible environmental and health threats Likely need for guidelines and regulations

Ocean Mining Ore deposits in the ocean Minerals from seawater Minerals in ocean sediments Hydrothermal deposits Manganese-rich nodules Mining issues in international waters Environmental issues

Hydrothermal Ore Deposits on the Ocean Floor White smoker Black smoker Sulfide deposit Magma Tube worms White crab White clam Fig. 12-15, p. 283

Finding Substitutes for Scarce Mineral Resources Materials revolution Ceramic substitutes High-strength plastics and composites Finding some substitutes may be impossible Some substitutes are inferior